Re: Culling

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Yair Kurzion (yair++at++polygon.engr.sgi.com)
Mon, 29 Nov 1999 13:11:41 -0800 (PST)


Hello Dimi !

> How do I prevent a pfGeode Node with many Geosets from beeing culled.
> This is needed because I update the geometry of the Geosets at run time
> and
> I guess that it would be quite expensive to compute the the Bounding
> Sphere
> needed for culling every frame.
> With culling enabled for that node, my geometry gets sometimes culled
> even
> though it is in the Viewing Frustum, because the Bounding Sphere is not
> right.

You can instruct Performer to always accept a node (as visible) by calling:

    pfNodeTravMask(node, PFTRAV_CULL, 0, PFTRAV_DESCEND, PF_SET);

This call will make Performer consider 'node' and all its descendents as
visible. Performer will NOT compute the visibility of this node and its
descendents (CULL may run faster, but the culled result will always contain
this extra geometry).

You can limit this behavior to the node alone by using PFTRAV_SELF instead of
PFTRAV_DESCEND (see man page).

Using a pre-CULL callback on the node (as previously suggested) works too.
However, it runs a little slower.

-yair

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